1. Field of the Invention
This invention relates to a linear motion bearing assembly capable of providing an infinite linear motion, and, in particular, to a linear motion rolling-contact bearing assembly.
2. Description of the Prior Art
A linear motion rolling-contact bearing assembly is well known in the art. Typically, such a bearing assembly includes a generally trough-shaped guide rail extending straight, a slider member which slidingly moves along the rail and a plurality of rolling members interposed between the slider member and the rail thereby providing a smooth running motion to the slider member. In this bearing assembly, there is normally defined a pair of endless circulating paths between the slider member and the rail each endless circulating path including a load section defined interposed between the slider member and the rail and a non-load section defined generally inside of the slider member by the remaining section of the endless circulating path. The rolling members are provided in the endless circulating paths so that the rolling members roll therealong indefinitely thereby providing an indefinite relative motion between the slider member and the rail.
In such linear motion rolling-contact bearing assemblies, balls or rollers are often used as the rolling members; and, the sliding members and/or rail are often formed from a thin steel plate. A typical linear motion rolling-contact bearing assembly using balls as the rolling members and formed from thin steel plates into desired shapes by plastic deformation is disclosed in Japanese Utility Model, Post-Publication No. 54-34093. Such a linear motion rolling-contact bearing assembly is light in weight, easy to fabricate and thus low in cost; however, it lacks rigidity and accuracy so that its applications tend to be rather limited. It is true that thick steel plates may be used to fabricate such a bearing assembly to obtain an enhanced rigidity and accuracy, but this brings about other disadvantages, such as excessive weight, short stroke, and bulkiness. In addition, since its weight becomes greater, its inertia also becomes greater, which prohibits applications which require high speed operation.